Capacitive Pressure Sensor

Abstract

A variable capacitance type pressure sensor is constructed by only using semi-conductor industry accepted metals and materials in the wetted surface. PCTFE or PTFE by injection molding or compression molding is used to join components together and provide sealing and electrical isolation. No oil filling is needed. The sensor can measure both differential pressure and line pressure. Implanted temperature sensor is used to do thermal calibration and temperature compensation.

What is claimed is: 
     
         1 . A pressure sensor comprising:
 a conductive diaphragm;   a pair of outside welding rings welded together with the diaphragm;   a pair of electrodes coupled to the pair of outside welding rings via polymer seams;   
       a printed circuit board mounted on the outside welding ring; and 
       a temperature sensor. 
     
     
         2 . The pressure sensor of  claim 1  wherein Polychlorotrifluoroethylene (PCTFE) or Polytetrafluoroethylene (PTFE) or other polymer is used to join electrode and outside welding ring together by injection molding or compression molding. 
     
     
         3 . The pressure sensor of  claim 1 , the profile of the polymer seam is curved or straight. 
     
     
         4 . The pressure sensor of  claim 1  wherein the electrodes and diaphragm form capacitors to measure differential pressure, the electrodes and PCB form capacitor to measure the line pressure. 
     
     
         5 . The pressure sensor of  claim 1  further comprising
 one or more ports formed on the pair of outside welding rings, wherein the ports expose the pressure sensor to pressure or vacuum sources or atmosphere, make the pressure sensor an absolute pressure sensor, gauge pressure sensor, differential pressure sensor or barometer. 
 
     
     
         6 . The pressure sensor of  claim 1 , the temperature sensor is used to do thermal calibration and temperature compensation. 
     
     
         7 . The pressure sensor of  claim 1 , wherein the pressure sensor is an absolute pressure sensor, a gauge pressure sensor, a differential pressure sensor, or a barometer.